Shock absorbers typically comprise a damping fluid cylinder and a piston assembly. The piston assembly typically includes a shaft having an inner end mounted to a vented piston housed within the cylinder. Vehicle shock absorbers are commonly constructed so that the outer end of the shaft, which extends through one end of the cylinder, is mounted to one portion of the vehicle and the cylinder is mounted to another portion of the vehicle The one end of the cylinder has a seal, which provides a sliding sealing contact with the shaft passing through the one end of the cylinder.
One problem associated with outdoor vehicles such as snowmobiles is that ice may accumulate on the piston shaft. This is a problem because the ice on the piston shaft may be forced past the resilient seals surrounding the piston shaft and contaminate the damping fluid within the shock absorber. Such contamination may result in corrosion of the internal parts of the shock absorber, which may result in its early failure, and in a change in the flow characteristics of the damping fluid to change the operational characteristics of the shock absorber. Accumulated ice may also damage or destroy the sealing effectiveness of the seals surrounding the piston shaft, thus further damaging the shock absorber. See U.S. Pat. No. 5,584,368.
The present invention is directed to a shock absorber including a sealing ice scraper assembly designed to remove ice from the piston shaft and to prevent ice and liquids, in particular water on the outside of the piston shaft, from entering into the interior of the cylinder.
A shock absorber made according to the invention includes broadly a piston assembly and a damping fluid cylinder having a first end and defining a damping fluid chamber therein. The piston assembly includes a shaft having a first shaft end within the cylinder and a piston mounted to the shaft towards the first shaft end. The piston is movable within the cylinder and divides the damping fluid chamber into first and second variable-volume parts. A restricted flow path is provided between the variable-volume parts of the cylinder. A sealing scraper assembly is mounted to the first end of the cylinder. The scraper assembly includes a sealing ice scraper member, used to remove ice from the shaft, having a generally cylindrical scraper surface. A gap of a desired size, typically quite small, is provided between the scraper surface and the shaft. A recess is formed into the scraper surface and houses an outer fluid seal between the scraper surface and the shaft. Therefore, any liquid within the gap is at least inhibited, if not prevented, from passing the outer fluid seal and into the damping fluid chamber.
The scraper assembly is preferably mounted to an interface housing mounted to the first end of the cylinder. The scraper member is preferably radially positioned by a resilient centering element captured between the scraper member and the interface housing. The scraper member may also be mounted to be free to shift axially. An inner fluid seal may be used to both seal the shaft and provide an axially-directed biasing force against the scraper member.